Simultaneous Biofuel and Electricity Generation Using CO2-Neutral Microbial Fuel Cell

Limited availability and the environmental impacts from fossil fuels require that we find alternative energy sources that are renewable and safe. The microbial fuel cells have gained renewed attention for the production bioelectricity and biofuel from renewable sources. We have developed a CO₂-neutral microbial fuel cell for producing bioethanol, algae oil, and bioelectricity simultaneously. In our system, beer yeast was fermented in the anodic compartment of the fuel cell. The CO₂ generated in the fermentation was introduced to the cathode as carbon source for microalgae, Chlorella vulgaris. The power generation was characterized using potentiodyanmic polarization, and intermitted energy harvesting scheme that uses cyclic charging and discharging of the capacitor. The power generation was correlated with the growth kinetics of the yeast and the algae. The algae oil was quantified using Soxhlet extractor with hexane as the solvent. The bioethanol production in the anodic compartment was measured using HPLC. The power generation was ~ 30 mW/m² of the electrode surface. We found that 40 g/L of ethanol could be produced in the anodic compartment. The algae oil production was 10% of the dry weight of the algae.